Fluid exchange system for controlled and localized irrigation and aspiration

ABSTRACT

The control of fluid introduction into and out of body conduits such as vessels, is of great concern in medicine. As the development of more particular treatments to vessels and organs continues it is apparent that controlled introduction and removal of fluids is necessary. Fluid delivery and removal from such sites, usually referred to as irrigation and aspiration, using fluid exchange devices that control also need to be considerate of potential volume and/or pressure in the vessel or organ are described together with catheter and lumen configurations to achieve the fluid exchange. The devices include several electrically or mechanically controlled embodiments and produce both controlled and localized flow with defined volume exchange ratios for fluid management. The applications in medicine include diagnostic, therapeutic, imaging, and uses for the introduction or removal of concentrations of emboli within body cavities.

CROSS-REFERENCE TO OTHER APPLICATIONS

This application is a continuation-in-part of, claims the benefit of,U.S. Provisional Patent Application Ser. No. 60/306,315, filed Jul. 17,2001.

FIELD OF THE INVENTION

The devices and related methods of the invention relate to thecontrolled introduction and removal of fluids in diagnostic, therapeuticand imaging applications within the body. Specifically, the inventionrelates to the advantageous use of a fluid exchange device incombination with a catheter to produce a system for controlledaspiration and irrigation and the selective and localized exchange offluids within a body conduit, for example, in the diseased region of ablood vessel having a blockage or lesion. The devices of the invention,and the methods enabled by the use of the devices, have severaldifferent components that can be used individually or integrated into asystem for use within an organ and within the vasculature of the bodywhere controlled and localized irrigation and aspiration are performedtogether as a therapeutic procedure or in tandem with a separatetherapeutic procedure.

BACKGROUND OF THE INVENTION

Irrigation and aspiration are clinically important in many surgicalprocedures when fluids are selectively introduced into and removed froma target site within the body, usually while a surgery or othertherapeutic medical procedure is performed. When the site of thetherapeutic treatment is inside a body cavity or in the vasculature ofthe body, such as in a blood vessel, the irrigation and aspirationfunctions require special apparatus and methods. Surgical andpercutaneous systems that both irrigate and aspirate have beendeveloped, and some of these systems are catheter-based such that theintroduction and removal of fluids is performed within an organ or avessel by using the catheter as the conduit to introduce and removefluids from a target site. As will be readily appreciated, the catheterallows the control elements to be remotely located, e.g., outside thebody while the actual irrigation and aspiration functions areselectively provided within the body by selectively orienting the distalend of the catheter to the target site. In such cases, as is the case inopen surgeries, the irrigation and aspiration functions accompany atherapeutic procedure that is performed at the target site along withthe irrigation and aspiration.

Catheter-based irrigation and aspiration systems are unique in manyrespects due to their use in clinical situations where blockages orlesions exist inside a blood vessel, such as a coronary or carotidartery, and dangers arise from the creation and release of emboli withinthe vessel. In many intravessel therapeutic procedures, the danger fromthe creation of emboli is an unavoidable aspect of the therapeuticprocedure. For example, lesions of atherosclerotic plaques inside ablood vessel are treated by several therapeutic procedures includingendarterectomy, atherectomy, the placement of intravessel stents,balloon angioplasty, surgical ablation of the lesion, thrombectomy, OCT,dialysis shunt clearing and others. However, while each of theseprocedures has great therapeutic value in treating the lesion, eachcarries the risk of creating emboli during the procedure. As with anyprocedure conducted in the cardiovascular system, the risk isparticularly great where plaque dislodged from inside a blood vessel cantravel to the brain causing serious brain injury or death. For example,treating lesions of the carotids necessarily involve high risk.Currently, carotid treatments are attempted together with deployment ofa filter to attempt to track emboli generated by or released from acarotid lesion. Unfortunately, crossing a carotid lesion with a filteror other structure can generate a cerebral ischemia or stroke. Schlueteret al. 2001, Circulation 104 (17) II-368. Moreover, studies have shownthat merely crossing a carotid lesion with a guide wire can generateemboli. Al-Mubarak et al.: Circulation October 2001 23:104 (17):1999-2002. Also, some lesions carry such a high risk of generatingemboli that therapeutic treatments are attempted only in the most severecases. Where a chronic total occlusion exists, the diagnosis isparticularly poor because it is impossible to place a structure distalof the occlusion such that emboli generated by the removal of theocclusion can be captured before circulating in the bloodstream. Suchocclusions can only be treated by removing the occlusion from theproximal side, where emboli removal is uniquely difficult. Accordingly,if the capability existed to dramatically reduce the dangers of embolicreation during therapeutic procedures inside a vessel or organ of thebody, the existing procedures would be safer and more widely practiced,and new procedures would be performed.

A variety of systems to contain and remove emboli have been proposedwherein a portion of a vessel that contains a lesion is segregated bytwo occluding members, typically two balloons, which are inflatedproximate and distal to the lesion to effectively seal the inside of aregion of the vessel containing a lesion prior to treatment of thelesion. Once treatment is complete, embolic particles such as dislodgedplaque are removed by applying suction between the balloons. However,the tissue affected by a lesion is notoriously delicate and thetreatment of the lesion has the capability to generate or release emboliwhenever any mechanical manipulation of the lesion occurs. Thegeneration and/or release of emboli is a concern virtually anytime astructure is passed through a susceptible vessel. Such circumstancesinclude the placement of a balloon or stent, the placement of a filter,or simply the use of a catheter or guide wire for imaging, diagnostic,or any other procedure. In many procedures, the internal portion of avessel is occluded to provide a segregated region of a vessel throughwhich fluid does not flow. Moreover, virtually anytime structures areinserted into the vessel, the generation of release of emboli is aconcern. For example, in the common practice of placing a stent insidean artery, a filter may be placed distally of the stent to attempt tocollect emboli generated when the stent is expanded to engage plaques orlesions inside the vessel. All devices placed distal involve thecrossing of the lesion. All crossings of lesions create emboli of somequantity and significance. Such systems cannot protect the patientagainst the potential harm inherent in the placing the device.Additionally, once the stent is in place, the filter must be removed bypulling it through the portion of the vessel in which the stent has beeninserted. This carries the risk that the filter will impact the vesseland cause the release of emboli and/or contact the stent and eitherdisplace the stent or similarly cause the release of embolic particles.The use of occluding members of any type has certain drawbacks. Anytimea structure is used as an occlusive member inside a vessel, thestructure must deform the vessel from the inside to create a seal aboutthe periphery thereof with the internal surface of the vessel. Forexample, to make the seal tight enough to prevent the passage of fluidand emboli past the balloon, the expansion of the balloon typicallydeforms the vessel outward and may disrupt plaque in and about the pointof contact between the vessel and the balloon. Moreover, any plaque thatbecomes dislodged outside the barrier formed by the balloon is releasedinto the blood stream because there is no mechanism distal of theballoon to remove the emboli. For this reason, irrigation and aspirationproximate to the lesion are particularly important.

To create a segregated region of a vessel, a two-balloon system may beused. However, certain disadvantages of a two-balloon system also arisefrom the placement of balloons on both sides of a lesion and the natureof the blood flow that occurs in the region of the vessel containing thelesion once the balloon is removed. At the point of contact between theballoon and the vessel, plaque may be compressed underneath the balloonand may become dislodged upon reestablishment of flow through thevessel. Furthermore, many clinicians have observed that the regiondistal of a lesion is more likely to exhibit plaque formation than theregion proximal of a lesion. Thus, the use of an occluding member distalof a lesion does not eliminate the risk of creating emboli that mayenter the vessel. The risk is particularly great when a second balloonis used because the balloon is not advantageously placed for the removalof emboli created by the use of the balloon itself and because theballoon must be removed by passing it across the lesion upon completionof a procedure. This drawback is present in all circumstances when aballoon is advanced across a lesion because, when any occluding memberis placed distally of the lesion, the occluding member must be drawnback across the lesion to remove the occluding member at the end of aprocedure. Each passage of an occluding member across the lesion, evenin a retracted or deflated state, carries a substantial risk thatadditional emboli will be produced.

Also, the placement of two balloons requires additional time to inflatethe second balloon and adds to the complexity of a device due to anadditional lumen that must be incorporated into the catheter to inflatethe balloon. In a finite number of cases, the occluding member that isdistal of a lesion, and is required to retain emboli in a defined areawithin the vessel, has been observed to fail, thereby releasing theemboli into the bloodstream. Because the second balloon is relied uponto prevent the flow of emboli past the region of the vessel containingthe lesion, the failure of the balloon is a critical event thatthreatens the health of a patient undergoing the procedure. Furthermore,due to geometric constraints, the second balloon often acts as the guidewire as well. When delivering tools to perform the therapeutic ordiagnostic procedure within the vessel, the balloon may move and disruptthe vessel wall. Introduction of tools and other manipulations of adistally located balloon can also result in deflating the balloon orotherwise causing the balloon to lose patency on the interior of thevessel.

Anytime that a balloon is placed distal to a lesion, the contact betweenthe balloon and the lesion carries the risk of damaging the vessel. Forthese reasons, the use of balloons inside the vessel is preferred to beminimized and the length of time and extent of contact between a balloonand the inside of a vessel should be reduced. Ideally, the balloon orother occluding member could be placed proximal to a lesion so that thearea containing the lesion would be isolated. To achieve this, theirrigation and aspiration functions would have to be provided by astructure that is positioned distal of the occluding element, such thatthe occluding element could be placed proximal of the lesion, and theaspiration and irrigation functions achieved distal of the occludingmember.

Even under existing technologies where aspiration and irrigation areapplied in a catheter based system, the parameters of fluid flow, aswell as the placement of the aspiration and irrigation ports relative toan occluding member, are important to the physiological outcome for anygiven procedure. For example, removal of fluid and/or embolic particlesby simple suction from within a body conduit may only remove a portionof the fluid present in the vessel and may leave emboli in place even ifall of the fluid is removed and replaced. Deposits of plaque and otherdebris that may exist inside a vessel have a tendency to adhere to oneanother and particulate emboli tend to adhere to the sidewalls of thevessel. Thus, a system that provides limited fluid exchange isparticularly unlikely to achieve a complete removal of emboli. Also,given that the interior walls of a vessel may have been contacted fromwithin during a therapeutic procedure, a high likelihood exists thatadditional particles may be dislodged upon the establishment of a robustfluid flow through the vessel.

Ideally, a system for aspirating and irrigating the interior or a vesselor organ would provide both fluid exchange and fluid flow parametersthat are at least similar to that experienced during ordinaryphysiological functions and preferably would create a turbulent fluidflow that would proactively assist in the removal of particles and otheremboli. Such a system would require both a catheter element thatachieved aspiration and irrigation as well as a fluid exchange apparatusthat would be coupled with the catheter to produce the desired fluidflow rates and other fluid parameters. Because of the wide variation inintravessel procedures and the location of disease, an irrigation andaspiration system would also be particularly useful if the catheterelement could be selectively positioned along a specified length of avessel where emboli may be created together with operation of the fluidexchange apparatus to control the irrigation and aspiration flow. Thiscapability in the catheter element is most readily created with only asingle balloon system having a separate, movable, irrigation andaspiration catheter.

In the prior art two-balloon system described above, where a region of avessel is segregated by a pair of balloons located both proximally anddistally of a lesion, the area of fluid flow is limited to the regiondefined by the placement of the two balloons. The problem isparticularly acute when a vessel is treated with a procedure thatinstalls a stent or manipulates the plaque in a vessel, such as with anangioplasty, where the lesion is physically manipulated as part of thetherapeutic treatment. Assuming that the therapeutic treatment issuccessful, the vessel is treated by virtue of expanding the interiorvolume and promoting the flow of blood through the vessel. Under thesecircumstances, the portions of the vessel distal of the lesion have beencontacted by a balloon and are then exposed to a higher volume of fluidflow than existed before the procedure. In the context of a typicalpatient, a vessel which had become slowly blocked due to the deposit ofplaque over a large number of years has been expanded by the treatmentof the lesion and this therapeutic treatment at an upstream pointsubjects the region in which the lesion is located and those downstreaminternal portions to a rate and volume of blood flow that has not beenexperienced in the many years since the vessel began to become occluded.Under these circumstances, an additional risk exists that plaqueslocated downstream from the lesion will be dislodged and will enter thecirculation causing serious injury.

As with ordinary irrigation and aspiration in an open surgery, theirrigation and aspiration that are applied through existing cathetersystems are typically regulated only by setting the positive or negativepressure that is applied to the aspiration or irrigation lumen of thecatheter and is in turn communicated to the distal end of the catheterto insert or remove fluid respectively. However, to create the specificfluid flow parameters that maximize the removal of emboli and the fluiddisplacement within a vessel, thereby establishing fluid change in thevessel in the most physiologically relevant manner, a specialized fluidexchange device would have to be created to regulate the fluid flowparameters of both the irrigation and aspiration functions of thesystem.

An ideal irrigation and aspiration system could be an additive componentto several other apparatus that are used in therapeutic, diagnostic, orimaging applications in the body such that the capability of the systemwould not be exclusive of other technologies that have been applied toenhance the safety of an intravessel procedure. Several differentapproaches apart from irrigation and aspiration have been attempted tophysically capture emboli downstream at a lesion, most notably throughthe use of filters. However, filters have inherent drawbacks that cannotbe completely eliminated. For example, embolic particles smaller thanthe filter pore size, commonly on the order of 100 microns evadefilters, which must not be so small that physiologically importantelements such as red and white blood cells are captured by the filter.Also, particles larger than the pore size tend to become trapped in thefilter such that the filter itself becomes an occlusive element andblood flow through the filter is impeded. Also, as described above foroccluding structures, whenever a filter is introduced distally to thelesion in a vessel, a finite probability exists that the removal of thefilter will generate emboli. Still further, where a stent is placed at alesion, the movement of the filter past the stent and through the vesselhas the capability to catch or displace the stent.

Although certain portions of the discussion herein are directed towardsa preferred embodiment of the apparatus of the invention used in anintravessel procedure, the devices and methodologies of the inventioncan readily be applied to non-vessel sites within the body such aswithin any body conduit such as an ear canal, colon, intestine, thetrachea, lung passages, sinus cartilages, or any internal volume whereina controlled and localized irrigation and aspiration function aredesired. For example, in a diagnostic colonoscopy an endoscope may beintroduced to aid in optical visualization of the site. However, thecolon responds to fluid pressure changes and thus while trying to clearthe field the tissue of note may move. To aid in this diagnosticsituation, a controlled introduction of a clear fluid could beintroduced in concert with an equivalent aspiration of dirty fluid. Assuch, the tissue may remain in the field of view while the processoccurs. For imaging purposes the introduction of a contrast agent whilesimultaneously extracting an equivalent fluid will allow a vessel ororgan to maintain its normal fluid level and pressure. As the imaging iscompleted, the same system could then return a more normal fluid to thesite while extracting the foreign contrast agent. Imaging “pig-tail”catheters are presently used to introduce contrast agents to vascularsystem, even though radiopaque contrast agents are known to maintain alevel of toxicity (Solomon, Kidney International, 1998, vol. 53, pp.230-242). If the field of contrast was introduced and extracted asproposed by Courtney, et al., the patient's exposure would besubstantially reduced.

SUMMARY OF THE INVENTION

The present invention provides control of both irrigation and aspirationfunctions at a selected location within a body cavity or conduit, suchas a target region of a blood vessel. The region of the vessel to whichan irrigation and aspiration function are provided may include both atherapeutic treatment site, the site proximal to the placement of aballoon, or a length of a vessel both proximal to and distal of a lesionwherein a surgical treatment was performed, where a diagnostic ortherapeutic procedure caused the insertion of a dye or other solution,such as a clot dissolver, or where a total chronic occlusion occurs.Because the irrigation and aspiration functions are performedsimultaneously, the fluid exchange apparatus of the invention is able tosimultaneously regulate both irrigation and aspiration in a manner thatadvantageously controls the fluid flow rates and fluid flow parameters.This capability can be achieved both by controlling the flow rates usingan electronic control system, as well as providing a mechanicalapparatus that controls irrigation and aspiration flows when actuated bya user. When the catheter and fluid exchange device are combined intothe system of the invention, the combination provides uniquecapabilities for treating or diagnosing a lesion contained within avessel. For example, the lesion may be pre-treated prior to thetherapeutic treatment which typically comprises ablation of a lesion orplacement of a stent or expansion of the diameter of the vessel, i.e.,through an angioplasty procedure. In a diagnostic embodiment, dye orother diagnostic markers can be infused distally of the occluding memberand proximate to the lesion while avoiding the potential hazards ofpassing a collapsed balloon across the lesion. This provides adiagnostic capability which has substantially reduced risk relative to atherapeutic treatment that requires expansion of an occluding memberdistal of the lesion. Because of the added safety margin, the diagnosticprocedures can be more readily performed without the risk of producingemboli and thus are a more available complement to the therapeuticprocedure.

Preferably, the system of the invention includes a catheter elementhaving specific features designed to facilitate the desirable fluid flowparameters when connected to the fluid exchange apparatus. Ideally, whencoupled with an apparatus that inherently provides controlled andregulated fluid flows for both aspiration and irrigation, the catheterworks in tandem with the apparatus to create both controlled andlocalized irrigation and aspiration through a catheter-based system. Forexample, the apparatus of the invention allow the user to control theirrigation and aspiration flow volumes, and by virtue of a speciallydesigned catheter system, provide improved fluid flow parameters thatfacilitate quantitative volume exchange within a vessel or other cavityand produce defined fluid flow parameters in a region bordered by anoccluding element. Accordingly, the aspiration and irrigation functionsprovided by the fluid exchange device can be added to several existingdevices such as balloon occluding elements or filters, or can be usedalone as a catheter-based fluid exchange system without any additionaldevice. Thus, the fluid exchange capabilities can be added to anexisting device such as a straight catheter or filter, or an existingdevice can be integrated into the remaining components of the presentinvention to provide the advantageous irrigation and aspirationfunctions as described herein. For example, to decrease time during atherapeutic or diagnostic procedure, the portion of the catheter elementproviding the irrigation function could be combined with a catheter usedto perform an angioplasty procedure.

When so integrated, the irrigation and aspiration functions of theinvention are located distal to the angioplasty balloon and the enhancedremoval of emboli is facilitated. Also, the location of the irrigationand aspiration lumens can occur such that the aspiration ports are onopposite sides of an occluding member or other structure such that adirect irrigant to aspirant volume exchange may or may not occur in thelesion of a vessel. In preferred embodiments of the system of theinvention, the catheter element provides turbulent, rather than laminar,flow within the vessel. Turbulence is introduced locally at the regionof fluid exchange within the body. In a turbulent flow, the velocity ata point fluctuates at random with high frequency and mixing of the fluidis much more intense than in a laminar flow. Turbulent flow isspecifically preferred because it reaches the walls of a body structureand facilitates both fluid exchange and dislodging of particulatematter. To reach the walls, the irrigation ports exit the catheterelement in the direction of the wall. To accomplish this, the catheterelement preferably has ports that exit orthogonal to the wall of thedistal end of the irrigation lumen of the catheter. The aspiration lumenmay establish a local laminar flow profile. This results in laminar flowabout the vessel.

Also, in a turbulent flow, the velocity at a point fluctuates at randomwith high frequency and mixing of the fluid is much more intense than ina laminar flow. This is of particular value when attempting to clear anysite of debris. Without turbulence, the flow along the sides of avessel/lumen is approximately 0. When trying to remove/clear or exchangefluids thoroughly is it imperative to facilitate mixing. Mixing can onlyreach the vessel walls through the application of turbulence. This isappreciated by the vessels as well, since turbulence can be achievedwith this invention without high-powered injection systems that carryphysiological risks associated with their inherent power and abnormallyhigh flow rates.

In more scientific terms, when a laminar flow is made turbulent, thenthe velocity will become more uniform and higher, and as a result, fluidparticles in the boundary layer can move farther downstream beforeseparation takes place. This turbulence is generally local to theirrigation area and controlled by the dimensions and orientation of theports of the irrigation lumen.

The flow and velocity exchange rate through the entire system is notaltered significantly since the turbulence is local area around theirrigation ports. But turbulence for an equivalent flow produces a muchmore uniform flow across the vessel. This results in higher velocitiesalong the wall where emboli and thrombus are known to be in residence.From a physiological relevance standpoint, blood clots, or thrombi, aremuch more likely to be released into turbulent than in laminar flow.(Berne & Levy, 2001, Cardiovascular Physiology, p. 126).

Because flow is proportional to viscosity, irrigation with any number offluids can increase the flow over just aspiration of the site. Forexample, the viscosity of blood is 5 times that of water in a vessellarger than 0.3 mm in diameter, (from graph 5-14, in Berne and Levy, p.129). The resulting combination of turbulence and the introduction ofvarious fluids allows for substantially variable fluid flows whichcannot be achieved without the combination herein disclosed.

Those of skill in the art will appreciate that the fluid exchangecapabilities and fluid flow parameters provided by the invention can beintegrated into a number of systems to provide irrigation and aspirationand essentially any physiological context where near quantitativeremoval of fluid or particles from a site is desired. As noted above,the enhanced fluid flow parameters can be strategically orientedrelative to the placement of an occluding member, such as a balloon, toeffectively remove fluids or solid matter either proximal to or distalof the occluding device. The catheter element of the apparatus can alsobe positioned to facilitate the removal of dyes, or therapeutic ordiagnostic compounds as part of the fluid exchange function of theapparatus of the invention.

In a preferred embodiment, the invention provides both irrigation andaspiration in a selected region of a vessel proximate to a lesion, butwithout any occlusion distal of the lesion such that the occludingelement may be both inserted and removed without passing across thelesion. Because of the design of the catheter-based system, a singlecatheter element may both aspirate and irrigate and may be moved withinthe vessel whether or not used in combination with other apparatus. Whenused in combination with an occluding element, the irrigation andaspiration factors may be fixed in place proximate to a lesion within avessel or may be movable such that a single catheter element having bothaspiration and irrigation functions can be advanced into an areaproximate a lesion and actuated to perform the irrigation and aspirationfunction both proximate to the lesion and distal to the occlusionelement. Similarly, if there exists a distal device (filter or occlusionballoon) this system can be activated to accomplish the followingoptimum clinical benefit. The irrigation ports being just proximal, butnot exclusively proximal, to the aspiration port, then the vessel can beirrigated actively with the local flow moving prograde. This drives theemboli up against a more distal occluder/filter and there the aspirationport evacuates the emboli. Used in concert with existing filters orballoons this results in optimum retrieval of emboli from the activeirrigation. This embodiment does not require a proximal occlusion forclinical benefit.

In procedures where emboli may be present, this device may be used aspart of a method to extract the emboli generated during either atherapeutic, surgical, imaging or diagnostic procedure. The volumeexchange provided by the current invention is also adapted to facilitateremoval of fluids within a measured portion of a vessel where vesseldimensions and fluid volumes are known. This device affords a simplemechanical means through which these may occur in concert. Primaryapplications have been identified that produce a 1:1 exchange of fluids,but further applications include pulsatile exchange rates and ratiosother than 1:1.

The control aspect of the invention is derived in part from measuredvolumes that may be inserted and removed through a catheter systemcomprising an irrigation lumen and an aspiration lumen in fluidcommunication with irrigation and aspiration port(s) that insert andremove a defined or predetermined volume of solution. The design of thecatheter and the fluid flow parameters achieved at the target siteproduce specific fluid dynamics within a vessel or body conduit thatpromote the removal of emboli and/or the near quantitative removal of afluid contained in the region of a body conduit. In a preferredembodiment, a catheter coupled to a fluid exchange apparatus is actuatedto create turbulence within the vessel or organ and proximate to theports or exit holes of the irrigation lumen. As described in detailbelow, the size and orientation of the ports and lumen changes the fluidflow parameters such that defined flow rates, volumes, vortices,turbulence and ratios of fluids exchanged within the body can be customdesigned for any application, vessel, or organ, as well as for specificdiagnostic, therapeutic or imaging applications. Because many of theembodiments of the invention are used within the cardiovascular system,the irrigation and aspiration function can be designed such that fluidsmove into the vasculature in a pulsatile manner as with the movement ofblood within the vessel caused by the beating heart. This type of fluidmovement and fluid exchange provided by the aspiration and irrigationfunctions of the invention is advantageous because the insertion andremoval of fluid in this manner exposes the vessels or other structuresto fluid flow that is physiologically relevant. In the sense that thevessel experiences fluid flow that is similar to that experienced afterthe therapeutic, diagnostic, or imaging procedure is performed and anyemboli that would be released following the procedure are more likely tobe released during the irrigation or aspiration process performed by thedevices of the invention.

As described in more detail below, the design also facilitates a definedfluid exchange rate, such as 1:1 volume exchange that avoids damage tothe vessel while producing turbulence to facilitate the removal ofemboli. Generally, turbulent flows provided by the device of theinvention are localized and controlled in both volume and location andare typically higher than that provided by the existing devices in termsof both flow and velocity. Target flows of 1 cc/sec/sec are relevant tovessels such as the vein grafts, flows up to 2 cc/sec are relevant forvessels such as the carotids. (Louagie et al., 1994, Thorac CardiovascSurg 42(3):175-81; Ascher et al., 2002, J Vasc Surg 35(3):439-44).

As noted above, an advantage of the invention is the generation oflocalized turbulence in the vicinity of the infusion catheter such thatvolume exchange within the vessel promotes the disruption of embolicparticles that are only loosely attached to the interior walls of avessel. This advantage is derived from both the design of the catheter,which affects the location in which fluids are inserted and removed intoa vessel or an organ, as well as the specific design and function of thefluid exchange apparatus that, when coupled with the catheter of theinvention, combine to produce improved fluid exchange and fluid flowparameters. For example, in an ordinary vessel that is roughlycylindrical within a defined axial distance along the length of avessel, the removal of liquid generally produces a laminar flow throughthe center of the annular structure of the vessel and the fluid alongthe walls of the vessel are largely left in place. With a turbulentfluid flow profile, the fluid introduced into the vessel causes anexchange between the irrigant the existing fluid that is localized alongthe vessel walls and generally causes a more thorough mixing of thefluids within the vessel such that a more complete fluid volume exchangeoccurs and the removal of embolic particles is enhanced.

Although the particular parameters vary according to the designsdescribed below, the fluid exchange achieved by the fluid exchangeapparatus and the irrigation/aspiration catheter results in an insertionand removal of a defined volume within a vessel. As described in furtherdetail below, the overall system is comprised of a fluid exchangeapparatus that may have a mechanical or electrical, or both, fluidexchange component that converts a defined volume of fluid exchange witha defined axial movement of the catheter such that the volume of fluidexchanged per measure of distance of axial movement of the catheterthrough a vessel is known. Preferred embodiments of the fluid exchangeapparatus are a substantially closed system wherein a reservoircontaining irrigating fluid is combined with a reservoir containing theaspirated fluid such that known volumes are exchanged through a systemthat is essentially “closed” except for the exchange site within thevessel. The terms “substantially closed” mean that the system is closedbecause the volume of fluid inserted as irrigant solution is removed asaspirant solution in a predetermined ratio and any deviance from theratio is attributed to only a volume of solution that is retained withinthe body at the target exchange site. For example, when a system of theinvention is applied to irrigate and aspirate fluid from within avessel, the system is substantially closed because the only differencebetween the fluid inserted as irrigant and removed as aspirant is thatwhich is purposefully left behind in the vessel. When the volumeexchange ratio of the device is set at a 1:1 ratio, the volumetricexchange of fluids is very near to equivalent. The fluid exchangeapparatus may also be actuated in such a manner that the flow producedby actuating the fluid exchange apparatus is a defined increment. Thus,a known volume of fluid is exchanged at the target site and theclinician knows with certainty the volume of irrigant fluid that isinserted as well as the volume of fluid that is aspirated out of thetarget site.

In one embodiment, the device of the invention provides a 1:1 ratio ofirrigation to aspiration fluid exchange such that the volume of fluidintroduced to a vessel or organ is exactly matched by the volumeremoved. Through control of the location and movement of the device ofthe invention, the interior of a vessel or organ can undergo a completefluid exchange by advancing the infusion catheter along the length of avessel where removal of fluid is desired. By this process, severalresults are achieved that are beneficial therapeutically. First, thevessel experiences a turbulence and a fluid flow that is physiologicallyrelevant in the sense that both the volume of fluid moving across avessel as well as the turbulence are similar to the parameters that thevessel would experience under blood pressure. This similarity hasseveral aspects. First, the turbulence that occurs in a vessel issimilar to the turbulence caused by the motion of blood moved by abeating heart. Second, the pulsatile nature of the fluid exchange isalso similar to the varying pressures and pressure profile caused byventricular contraction and the ordinary movement of blood throughoutthe arterial system. Finally, these specific fluid flow characteristicsare achieved without producing substantially increased pressures withina vessel and without distending the vessel through the application ofincreased fluid pressures. Thus, the combined irrigation and aspirationof controlled volumes of liquid treat the vessel with a physiologicallyrelevant fluid profile.

Because the device of the invention offers the ability to introduce andremove a defined volume of fluid, the clinician can have a high degreeof certainty that the entire internal volume of a region of a vessel hasbeen rinsed with an irrigation fluid by knowing the approximate internalvolume of the vessel and the length of the vessel in which irrigationand aspiration are performed. For example, assuming that a specifiedregion of a vessel has an internal volume of 20 ml over a defined axiallength. The device of the invention can be used to insert predeterminedvolumes of solution greater than, less than, or equal to 20 mls over thedefined length of the vessel. Depending on the clinical environment, theratio may be altered to remove greater volume by establishing a smallerratio of irrigation to aspiration. One could, for example, irrigate withone volume of solution while removing twice the volume through theaspiration portion of the system to yield a 1:2 irrigation to aspirationvolume.

In a preferred embodiment, the fluid exchange device has the ability toperform a controlled exchange of fluid with predetermined ratiosincluding a 1:1 irrigation to aspiration ratio and varying ratiosparticularly values ranging between a 1:2 irrigation to aspiration ratioand a 2:1 irrigation to aspiration ratio. Preferably, this is achievedby having irrigant and aspirant reservoirs of defined volumes built intothe fluid exchange device. However, the device can also feature aselectable control that alters the ratio of fluid exchange between aminimum and a maximum as a function of the operation of the device. Inthe mechanical embodiment of the fluid exchange device, each actuationof the device may cause a defined volume of fluid to be propelledthrough an outlet that is in fluid communication with the irrigant lumenof a catheter element. In combination, the device also features anaspirant reservoir which is expanded by a predetermined volume relativeto the volume of the irrigant that is expelled.

The control of these parameters, in some aspects, by the fluid exchangedevice is the result of designing the fluid exchange device to cooperatewith both conventional catheters as well as those specially designed toproduce turbulent flow at the target fluid exchange site. The fluidcontrol functions of the exchange device can also cooperate with thecatheter element by incorporating the capability for the fluid exchangedevice to control motion of the catheter, specifically axial movementwithin a body conduit such as a blood vessel. In this embodiment, thecatheter element is coupled to the actuation of the fluid exchangedevice by a coupled translation mechanism wherein, as described infurther detail below, each actuation of the device results in automaticadvancement or retraction of the catheter. Thus, a defined exchange offluid volume at the target site occurs in combination with advancementor retraction of the aspiration and/or irrigation element of thecatheter by a defined distance. In this manner, repeated actuation ofthe device provides a step-wise motion of the irrigation and evacuationfunctions and can insure a near quantitative volume exchange over adefined distance. As will be apparent from the following description,this aspect of the invention provides the ability to insert and/orremove a defined volume of fluid distal of an occluding member given anapproximate knowledge of the dimensions of the vessel. As with the otherembodiments, the operation of the system may provide fluid exchange witha pulsatile fluid flow by virtue of the application and dissipation ofpressure achieved through the catheter.

Any number of designs for the fluid exchange apparatus can be used toprovide controlled volumes of irrigation and aspiration fluids, throughthe catheter element of the invention to the target exchange site. Thesimplest embodiment of the invention provides a squeeze bulb wherein theirrigant and aspirant reservoirs are typically separated by a membraneand are in fluid communication with a irrigation and aspiration lumenthat communicate fluids to and from the target site. In this embodiment,a one-way valve is provided preferably on both the irrigant and aspirantside of the fluid flow, to prevent aspirated fluid from flowing back tothe target site. In another embodiment, a mechanical device causespressure to be exerted on an irrigant reservoir that is in fluidcommunication with an irrigation lumen that provides fluid flow to atleast one irrigation port at the distal end of a catheter. The catheterelement also comprises an aspiration lumen, that may or may not beintegral with the irrigation lumen, and which facilitates fluidcommunication of the aspirant fluid back to an aspirant reservoir. Inthis embodiment, the irrigant is expelled from a reservoir by theapplication of mechanical force to reduce the volume of the irrigationreservoir and the mechanical force is preferably coupled to an expansionof the volume of the aspirant reservoir to yield a defined fluidexchange between the irrigant reservoir and the aspirant reservoir.

Those skilled in the art of medical devices will appreciate that all ofthe component parts of the invention are assembled from biocompatiblematerials, typically medical plastics or stainless steel. The syringesdescribed below may be ordinary medical-use syringes or may be customfitted to be replaceable and to fit engagingly with the fluid exchangeapparatus. An irrigant reservoir that is integral with the device may bepre-filled or a pre-filled syringe may be used to supply the irrigantfluid. In either a stainless steel or plastic embodiment, the device isstabilized. Typically, stainless steel devices are exposed to heat andsteam in an autoclave, while medical plastics may be exposed to gammairradiation or microbicidal gases such as EtO. The methods of theinvention specifically include the use of any component of the system ofthe invention followed by sterilization of the components, or the entiresystem, and re-packaging for subsequent use. Although plasticembodiments are designed for single use, sterilization may be performedto functionally reconstruct the utility of the device after use with apatient.

In one preferred embodiment, a hand-held mechanical device is actuatedby a trigger to insert and remove controlled volumes of fluid throughthe catheter element. The hand-held embodiment is comprised of anactuator such as a movable trigger that is mechanically operated bybeing grasped by the hand and pulled towards a stationary structuralhousing of a complementary portion of a housing to cause a reduction inthe volume of an irrigant reservoir and, accordingly, fluid movementthrough an irrigation lumen and out one or more irrigation ports at thedistal end of a catheter. Fluid provided to the target site in thismanner is recovered through one or more aspiration ports andcommunicated through an aspiration lumen and returned to the aspirantreservoir of the fluid exchange device. The irrigant and/or aspirantfluids are preferably contained in a sealed reservoir system such as acylindrical chamber having a piston and a rod wherein the piston ismechanically coupled to the actuating element. Motion of the actuatingelement transfers force to the piston and causes contraction of theirrigant reservoir and expulsion of liquid from the reservoir.Simultaneously, the motion of the actuator causes the expansion of thevolume of the aspirant reservoir and causes withdrawal of fluid throughthe aspiration lumen and into an aspirant reservoir. In such anembodiment, the actuation of the trigger may translate into varyingamounts of fluid flow depending on the mechanical expedients used. Asingle actuation of the trigger may translate into an incrementalmovement of a piston that exerts force on an irrigant and/or aspirantreservoir. By the use of several conventional mechanical apparatus, suchas a ratchet and gear mechanism, a lever and pivot system, or others,the mechanical fluid exchange device exerts a direct control over theexchange of fluid communicated through the irrigation and aspirationlumens. The control of the fluid and the particular features can beprovided in several designs that achieve the same function. For example,in addition to the hand-held apparatus described below, the force neededto create the fluid flow in both the aspiration and irrigation sides ofthe system could be provided by a mechanical foot pump, vacuum pump orvirtually any component device that provides controllable fluid flow.Moreover, to provide total reproducibility in the operation of thesystem, a console controlled by a computer with appropriate commands ora software program is readily used to produce the same fluid flows,fluid exchange parameters, including exchange ratios, and essentiallyall of the functions of the purely mechanical embodiments describedbelow. Therefore, those of ordinary skill in the art will appreciatethat any number of mechanical or electrical variations give rise to thesame fundamental principle wherein controlled volumes are applied to atarget site through a segregated irrigation and aspiration system,preferably comprised of irrigation and aspiration lumens that passthrough at least one catheter element and engage in fluid exchange at atarget exchange site by virtue of specially designed irrigation andaspiration ports at the distal end of the catheter element.

By altering the dimensions of the irrigation reservoir and theaspiration reservoir, the ratio of fluid exchange between the irrigantand aspirant reservoirs is altered and, accordingly, the fluid exchangein the target vessel is adjusted. For example, where the irrigantreservoir and aspirant reservoir are of identical sizes, an actuation ofthe fluid exchange device may yield a 1:1 fluid exchange within thetarget vessel. Where, as described above, a different fluid exchangeratio is desired, the difference in the ratio may be achieved by acorresponding difference in the dimensions of the irrigant and aspirantreservoirs that are emptied and filled through the operation of thefluid exchange device. Also, variations in ratio may be accomplished bycorresponding changes in the dimensions of in-line chambers as describedbelow. Likewise, with a 1:1 ratio, equal volumes of irrigant andaspirant are exchanged in a single cycle of the fluid exchangeapparatus. In the 1:1 embodiment, the entire irrigation and aspirationvolumes may be exchanged within a defined number of cycles of theapparatus. For example, one may provide that each cycle of the hand-heldapparatus provides 1 ml of irrigant volume and removes 1 ml of aspirantvolume. By providing an irrigation and aspiration reservoir with knownvolumes, a known number of cycles translates into a known volume ofirrigation and aspiration. As noted above, in one specific embodiment,the actuation of the device also causes translation of the infusioncatheter along a defined axial path such that a known volume of solutionis provided in both the irrigation and aspiration aspects as a functionof the distance that is traveled by the infusion catheter.

Clearly, the irrigation reservoir may advantageously be divided intosubparts and is not limited to ordinary aqueous solutions used in asurgical context. Given the utility of the present device for diagnosticand imaging applications, the irrigation reservoir could be filled withdyes, contrast agents, or other solutions that aid in the diagnosis ortreatment of the vessel. Given that the fluid exchange device of theinvention also provides unique fluid flow parameters, the irrigationreservoir could contain therapeutically valuable solutions such asheparinized ringers lactate, streptokinase, urokinase, tissueplasminogen activator, or other thrombus or emboli treatment fluids thatare used to perform the therapeutic procedure on the internal portion ofa vessel or organ. Given the ability to specifically tailor the fluidexchange parameters for a target vessel, the device offers the abilityto use therapeutic compounds that might not otherwise be availablebecause the clinician can be certain of the enhanced ability to removesolutions introduced via the irrigation reservoir. The fluid exchangeapparatus can also be used to promote absorption of a therapeutic layeron a vessel wall. If a drug coated stent is produced that can reabsorbdrugs after they have eluted, then with this device a high concentrationof the drug can be introduced and pooled about the stent for a briefperiod. This high dose may then be absorbed or bonded back to thestructure or one of its components and thereby recharging the drugcoated stent.

Finally, in a system where it may be advantageous to have ratios otherthan 1:1 in the system it is also directly applicable. For example, inanother vascular situation a virtual shunt may be created where aproximal fluid can be circulating and a fluid is infused distally. Thiswould involve a ratio of greater than 1:1 irrigation to aspiration.Furthermore such an arrangement could introduce a second fluid to be theprimarily distally delivered fluid. The second fluid could be blood,blood substitute, plasma or oxygenated fluid to produce a virtual shunt.

In the diagnostic use of optical coherence tomography, OCT, the fieldsof applications are presently limited by the need for a clear field.Similarly the use of intravascular ultrasound, IVUS, is somewhat limitedby the attenuation associated with the blood in vivo. A substantialvolume exchange of the vessel region in proximity of the distal end ofthe OCT or IVUS catheter would provide the opportunity to replace bloodor other fluids with transparencies other than that found in blood, thusimproving and/or modifying the imaging quality.

DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the basic components of the device necessary forimplementation with the optional inclusion of components that generate aminimum flow rate of exchange, components that incorporate an upper flowrate of exchange, and a configuration where a combination of flowthreshold and ceiling provide a flow rate bandwidth.

FIGS. 2A-2D are cross-sections of a vessel showing the catheter elementof the invention with aspiration and irrigation lumens combined in thesame catheter element and terminating at an aspiration and irrigationport, respectively. FIG. 2A is a section of the catheter showing theaspiration and irrigation lumens. FIG. 2B is insertion of the catheterelement into an exchange region established at a terminal lumencharacterized by a total occlusion such as a clot, lesion, abscess, aball of wax or a body conduit or organ that is closed-ended such as anear canal. FIG. 2C shows a cross-section of the system with an occlusionballoon to establish a defined region of fluid exchange between theirrigation lumen and the aspiration lumen. FIG. 2D shows one example ofthe placement of an aspiration port and an irrigation port that is influid communication with the aspiration lumen and irrigation lumen,respectively.

FIGS. 3A-3F show the catheter element in various configurations andillustrate the difference between laminar and turbulent flow. FIG. 3A isa catheter element having an occlusion member and comprising anoccluding guiding catheter having an aspiration lumen and with theirrigation provided by a separate catheter to aid in defining a field ofexchange. FIG. 3B shows a catheter element providing an isolated,localized region for fluid exchange that is maintained by irrigationoccurring both proximal and distal to a centrally disposed aspirationport. FIG. 3C shows a typical laminar flow that fluids will naturallyassume when passing through a cylindrical tube. The flow velocities arehighest at the center of the tube and approach zero velocity at thewalls of the tube. The length of the arrows indicate the magnitude ofthe velocity.

FIG. 3D shows the turbulent region of flow created by a catheter elementof the invention adjacent to a region where the flow transitions to alaminar flow, but still has a comparatively higher velocity along thewalls of the tube. At a distance from the irrigation ports, the flowachieves laminar flow.

FIG. 3E shows a catheter element with 3 rows of perfusion holes. Thefigure illustrates how the turbulent flow is most pronounced in theimmediate vicinity of the infusion ports and begins to assume laminarcharacteristics until the next row of infusion ports is encountered. Inthe region designated “A,” turbulent flow is provided by the irrigationport geometry. In region “B,” flow is tending toward laminar flow. Inregion “C,” laminar flow is established.

In FIG. 3F, the various regions of flow show the relative distancesnecessary for each activity. The transition region has typically beenshown to be about the same length as the perforated region of thecatheter element.

FIG. 4A is a schematic of an embodiment of the fluid exchange devicethat produces pulsatile flow through the application of leverage to ahand-held unit that is actuated to communicate force to the irrigantreservoir and which collects fluid in the aspirant reservoir. FIG. 4B isan embodiment that accepts interchangeable fluid cartridges, similar tosyringes, for irrigation and aspiration and where the exchange rates canbe altered to other than a 1:1 ratio. In this example there is a 2:1ratio of irrigant to aspirant dictated by the relative sizes of thefluid cartridges.

FIG. 5A is a fluid exchange device incorporating a segregate irrigantreservoir that uses different types of irrigants, while FIG. 5Bsegregates the irrigant fluid into a sample to be inserted both proximalto and distal at a point of the target site.

FIG. 6 is a tabletop version of the fluid exchange device that issuitable for either a mechanically drive hand system or anelectronically controlled, pump-driven system, including an optionalin-line air trap for the irrigant and a filter for the aspirant.

FIGS. 7A and 7B are a grip lever activated embodiment of the hand-heldfluid exchange device of the invention wherein the actuation of atrigger relative to the body of the handle translates into the motion ofa piston that propels fluid from the irrigant chamber and collects fluidin an aspiration chamber (not shown).

FIG. 8 is a preferred embodiment of the hand-held fluid exchangeapparatus of the invention having a spring tensioned trigger mechanismthat is actuated by manual motion of the trigger relative to the body ofa handle. Actuation causes linear or incremental motion of a dedicatedirrigant and aspirant carriage that move in opposite directions tocontrol the force supplied to the irrigant and aspirant reservoir,respectively.

FIGS. 9A and 9B illustrate an embodiment at the hand-held fluid exchangedevice having an adjustable pivot point on a trigger to producedifferent flow rates and peak pressures.

FIG. 10 is an embodiment wherein the control of the movement of pistonsthat propel fluid from a cylindrical irrigant reservoir and into anaspirant reservoir is provided by a ratchet mechanism.

FIG. 11 is a fluid exchange device with two chambers, such that both anirrigation and aspiration chamber are arranged to operate in concert,with one filling and one expelling fluid in each direction and havingseparate input and output pathways for connecting to the reservoir andlumen elements.

FIGS. 12A and 12B show the apparatus configured as a compressible ballsqueezed by the hand with the internal volume divided into irrigant andaspirant chambers and designed to be connected in-line with irrigationand aspiration lumens and reservoirs.

FIGS. 13A and 13B are an embodiment wherein the fluid exchange device isa hand ball pump configured with an internal reservoir of irrigant fluidand a flexible member to separate the irrigant from in-flowing aspirantfluid. This device is initially loaded with a volume of irrigant thatencompasses most of the initial internal volume of the ball and whichflows through the target site to the internal aspirant reservoir. FIG.13C is an embodiment having a substantially rigid external housing andan internal balloon. The interior of the housing is filled with fluidand an internal balloon containing air or a non-volatile gas. Avolumetric pump changes the internal configuration of the balloon toforce fluid from an internal irrigant reservoir to an internal aspirantreservoir.

FIG. 14 is a device with both irrigant and aspirant chambers combinedinto one housing separated by a movable piston into two distinctchambers to allow for the simultaneous rinsing and aspirating.

FIG. 15 shows a slidable and threaded combination configuration where anirrigant can be driven out and an aspirant simultaneously drawn in byboth a sliding and a screw-type mechanism. The sliding provides grosstravel and the rotation of the member about the axis produces afine-tuning mechanism.

FIG. 16 is an embodiment of the fluid exchange device that can becomprised of as few as the structural elements that preferably attach toa cylinder body of one reservoir and piston of the other.

FIGS. 17A and 17B are a mechanical fixture for providing aself-advancing or retractors catheter element in combination with thefluid exchange device.

FIGS. 18A-18C are an embodiment of the invention with a stagingcapability such that the means for aspiration and irrigation are linkedmechanically to travel in equivalent and opposite directions.

DETAILED DESCRIPTION OF THE INVENTION

The present invention may be used in a number of different environmentsand for a variety of purposes including, but not limited to allphysiological uses of peristaltic or other pump for aspiration andirrigation including, IVUS, OCT, angioplasty, endortarectomy, cardiacstent placement, vessel treatment, diagnosis and repair, surgicalplacement of non-cardiac stents, insertion of pig-tail catheters, earrinsers, etc. The following detailed description is exemplary ofpossible embodiments of the invention.

Referring to FIG. 1, a schematic representation of the invention showsthe basic components of the device necessary for implementation. Thecore fluid exchange or activation system maintains a substantiallyclosed loop system with the target site for fluid exchange, e.g. thesite within the body where aspiration and irrigation are applied. Theirrigation component of the invention is conveniently provided by adedicated irrigation reservoir 1, particularly when the fluid exchangesystem is the mechanical embodiment described in greater detail below.The exchange site is in fluid communication with the fluid exchangesystem via the irrigation lumen 2 and the aspiration lumen 3 which haveexit or entry ports (not shown) at the distal end of each lumen. Theaspiration component may also feature an aspiration reservoir 4 in fluidcommunication with the aspiration lumen 3 and aspiration ports (notshown) such that fluids removed from the exchange site are stored in theaspiration reservoir 4. As is apparent to one of ordinary skill in theart, the irrigation 1 and aspiration 4 reservoirs may be controlledelectronically by valves or pumps to provide the controlled fluidexchange ratios described herein. Thus, while the embodiments of theinvention featuring fluid exchange apparatus that are mechanicallycontrolled by the user are preferred in certain versions of any system,controlled rate of fluid exchange at a target site may be used in asystem of the invention. Alternatively, fluids in the aspirationreservoir 4 may be discarded. In one embodiment of the invention, fluidscommunicated from the target exchange site through the aspirationcomponent of the invention are analyzed for chemical or particulatecontent to determine a level of removal of fluids or solid matter fromthe exchange site.

Referring again to FIG. 1, an optional configuration of the componentsincludes a flow valve 6 that produces a minimum lower threshold forirrigation flow. This minimum delivery flow is beneficial to ensure aminimum amount of exchange flow when the clinical indication dictatesmaintaining a minimum flow through the irrigation catheter. The flowthreshold insures that the fluid exchange does not fall below apredetermined ratio as described herein. For example, although 1:1 fluidexchange rates are provided in several embodiments described herein, theexchange ratio may be altered such that a larger volume of fluid isaspirated compared to that which is used for irrigation or vice versa.Under such circumstances, the fluid exchange ratio would vary to, forexample, a 1:2 irrigation to aspiration ratio under circumstances wherea larger volume of liquid is desired to be removed from the exchangesite.

The components of the invention could also incorporate an upper flowrate of exchange or flow ceiling 6. When conditions dictate that thereis motivation to limit the velocity or overall flow parameters during ausage, a configuration that provides an upper limit may be provided.Accordingly, this embodiment would apply where a larger volume of fluidwas desired to be inserted by irrigation compared to that which isremoved by aspiration and the corresponding irrigation to aspirationexchange ratio would be increased to, for example, 2:1. The combinationof a flow threshold and flow ceiling capability provide a flow ratebandwidth yielding a range of values between two extremes. In thisembodiment, the exchange site can be irrigated and aspirated at aconsistent level that is either fixed or varies within a range. This mayalso allow the activation system to sustain a change in the pressurelevel at the exchange site while delivering irrigant fluid or removingaspirant fluid at a steady rate or within a range of rates. As will beappreciated by one of ordinary skill in the art, the irrigation side ofthe system of the invention requires active force provided by the fluidexchange apparatus such that irrigant fluid flow is established at thetarget site. However, while the aspiration side may also be controlledthrough application of force to withdraw fluid from the target site, theaspiration side may also be passive such that the inherent pressure atthe target site propels the aspirant fluid. The inherent pressure istypically provided both by the fluid pressure inside the body, e.g. theblood pressure within a vessel, and the pressure of the irrigant fluidentering the target site. This characteristically passive flow may bedescribed as an efflux flow, see U.S. Pat. No. 4,921,478 which isspecifically incorporated by reference herein. The passive flow ofaspirant fluid is one way through the aspiration lumen and the fluidpathway is comprised of one-way valve, such as conventional duck billvalves having a minimal cracking pressure to allow passive fluid flowwhile preventing retrograde flow through the aspiration side of thesystem. This capability provides for constant extraction of embolicparticles throughout a clinical procedure while irrigant fluid flow ismaintained and/or when fluid existing at the target site flows fromendogenous body pressure.

FIG. 2A is a cross-section of a catheter element 7 of the invention atthe exchange site. The irrigation lumen 2 in this configurationterminates at or proximate to the distal end of the catheter element.While the aspiration lumen 3 terminates proximally and both lumensterminate with exit ports 8,9. FIG. 2B depicts the insertion of fluidinto an exchange region at a terminal lumen. The irrigation port 6 inthis depiction is dislodging a terminal occluding clot. The terminalocclusion may include but is not limited to a clot, lesion, abscess, aball of wax or an ear canal. In such situations, simple aspiration maynot eliminate the lesion and a non-traumatic irrigation of the lesionwith a therapeutic formulation, in concert with aspiration after animproved treatment methodology. For example, even if the irrigationfluid is able to produce a substantial breakdown of a terminalocclusion, the occlusion itself must still be cleared. Moreover, thecombination of irrigation and aspiration to yield fluid exchange afterthe ability to introduce pharmaceutical agents proximate to theocclusion and the ability to remove the agents before they enter thebloodstream. A specific example of this is a thrombolytic agent used toremove the occlusion or potentially dangerous thrombus, wherein thethrombus or occlusion must be both treated and removed to treat thecondition and wherein the necessary dosage of the agent exceeds thatwhich could otherwise be introduced without drug-related toxicity.

FIG. 2C is a cross-section of the catheter element of the systemincorporated with a proximal occlusion balloon 11 to establish a definedregion of fluid exchange. This configuration may be useful for, but isnot limited to, occluding flow, limiting a diagnostic. agents field ofdeployment or limiting the bodies exposure to a high intensity agent. Adedicated balloon lumen 12 is provided for inflation of the occludingdevice. FIG. 2D is the catheter element of the system of the inventionhaving an occlusion member 11 to aid in establishing an exchange siteand having irrigation and aspiration functions distal to the occludingmember wherein the arrows depict the general direction of fluid flow,distal to proximal, relative to the occluding member 11.

FIG. 3A is the device incorporated with a combined aspiration lumen 3and occluding element 11 integral in the same catheter element with theirrigation driven by a separate catheter 2 to aid in defining a targetsite or field of fluid exchange. The irrigation lumen's 2 independenttravel affords a means of adjusting the location of the fluid exchangesite while maintaining the occlusion at a predetermined location.Furthermore, a treatment, diagnostic or imaging tool (not shown) canalso be affixed to the irrigation catheter 2. This is productive wherethe resident fluids are desired to be replaced with a dye or contractagent and then removed in turn prior to re-establishing normal bloodflow. In optical coherence tomography (OCT), for example, it isadvantageous to introduce and remove a low attenuating fluid. FIG. 3B isa fluid isolated region that is maintained by irrigation occurringthrough ports 8 located both proximal and distal to the aspiration port9. This configuration presents a means of maintaining a controlledintroduced field of fluid between the proximal and distal irrigationports 8. As in the embodiment of FIG. 3A, a treatment, diagnostic orimaging tool could be attached or moved along in concert between theirrigation ports. Referring to FIG. 3C, a catheter element (not shown)that merely inserts and removes fluid from a vessel achieves onlylaminar flow in the direction of the arrows and with velocityillustrated by the size of the arrows. Near the vessel wall the totalfluid flow approaches zero such that fluid containing emboli at thewalls is not disturbed and loosely affixed emboli remain in place. FIG.3D is a preferred embodiment of the catheter element of the inventionhaving orthogonally disposed aspiration ports 8 located at the distalend of the catheter element 7. The region “A” experiences turbulentflow, while region “B” experiences a flow profile that is in transitionfrom turbulence to laminar flow. FIG. 3E shows a series of irrigationports 8 spaced at intervals along the length of the distal end of acatheter 7 such that either turbulent flows, designated as “A” orregions where turbulence is transitioning to laminar flows, designatedas “B” are established along a length of the catheter 7 to substantiallyeliminate areas of laminar flow. FIG. 3F shows a configuration whereinthe irrigation ports are provided as a perforated region 8′ at thedistal end of the catheter 7. The arrows indicate the direction andmagnitude of flow showing that the perforated region establishesturbulence in a defined region, and as the distance away from theperforated portion 81 increases, the flow reverts to a laminar flow at acertain distance along the length of the vessel.

FIG. 4A is an embodiment of the device 10 that produces pulsatile flowthrough the application of a mechanical force to an apparatus thatpropels fluid through the catheter element of the invention. In use, theaction of a trigger 20 pulled toward a handle 21 exerts a force on adedicated irrigant piston 22 that compresses the irrigant reservoir 1thereby reducing the volume of the irrigant reservoir 1 and forcingfluid through the irrigant lumen (not shown) and simultaneouslywithdraws the dedicated aspirant 23 piston of the aspirant reservoir 4to accomplish the fluid exchange at the target site. Actuation of thetrigger 20 may cause the relative motion of the pistons 22, 23 byconnection handle to a ratchet or other gear mechanism that provides theexertion of force in an incremental amount based on the actuation of thehandle in a cyclical fashion. See e.g. FIG. 10 below and accompanyingtext. As shown in FIG. 4A, the irrigant and aspirant reservoirs mayadvantageously be provided by conventional syringes or similar devicesthat provide for fluid containment and the controlled application offluid flow. The syringes of FIG. 4A are merely examples of the use ofreplaceable cartridges that may be readily inserted and removed from thedevice. Such cartridges are particularly useful when pharmaceuticallyactive solutions are pre-filled and used in specific clinical procedureswhere medicaments are provided to a body conduit or vessel by the systemof this invention. In this respect, the use of this invention allows theselective introduction of pharmaceutical compositions of any type duringthe performance of an ordinary irrigation and aspiration operation. Inthe embodiment of FIG. 4A, the syringes comprising the irrigantreservoir 1 and aspirant reservoir 3 may be removably inserted into thehand-held fluid exchange apparatus 10 and used to both provide and expela predetermined volume of fluid through the target exchange site. Inthis manner, both the volume and content of the irrigant fluid can becontrolled by exchanging syringes and the contents of the aspirantreservoir can be retained and analyzed for fluid or particular content.The operation of preferred embodiments of the hand-held embodiment ofthe invention is also described at FIGS. 7-10 below and the accompanyingtext.

FIG. 4B is an example of interchangeable fluid cartridges 24 a 24 b,similar to the syringes described in other embodiments, for irrigationand aspiration. As described in greater detail herein, the irrigant 1and/or aspirant 3 fluid reservoirs may be provided by cartridges orreservoirs of differing sizes to accomplish the predetermined volumeexchange ratio desired for the particular clinical indication. In theembodiment of FIG. 4B, the irrigant fluid cartridge 24 a has double thevolume of the aspirant cartridge 24 b thereby providing a 2:1 fluidexchange ratio of irrigant to aspirant at the target site. In thisrespect, the loop established by the fluid exchange system is not acompletely closed loop, but is described as a substantially closed loop,in that a difference exists between the volume expelled through theirrigant reservoir 1 via the irrigant lumen 2 and into the exchange siteversus the difference in the aspirant volume taken up through theaspirant lumen and into the aspirant reservoir 40 although the volumesare not identical, the volumes are predetermined and known withcertainty as is the volume of fluid that remains at the target site,which is the difference between the volume of the irrigant fluidintroduced to the site and the volume of the aspirant fluid removedtherefrom. As in the embodiment of FIG. 4A, the irrigant fluid cartridge24 a has a dedicated piston 22 for expelling fluid from the cartridge.The aspirant cartridge 24 b similarly has a dedicated piston 23 forcollecting fluid introduced to the aspirant reservoir via the aspirationlumen 3. In this specific embodiment, more irrigant fluid is introduceddue to the larger cross-section of the irrigant cartridge 24 a while theoverall length of the cartridge that fits into the fluid exchangeapparatus remains constant. This technique for providing varying fluidcartridge volumes is advantageous when the irrigant and aspirantcartridges are replaceable in a fluid exchange device.

FIG. 5A is a revolving cartridge 25 that can rapidly provide a series ofirrigant solutions. This revolver-style orientation of irrigant solutionis advantageous for delivery of a sequence of different fluids or fordelivery of a pharmaceutical composition at an intermediate point duringa procedure. In use, the revolving cartridge 25 is oriented such thatthe series of irrigant fluids 24 b, 24 c, 24 d are positioned in linewith the dedicated irrigant reservoir piston 22 to expel the selectedirrigant solution placed in line with the piston 22. Under certainclinical circumstances, the application of the system of the inventionmay provide an ordinary rinsing solution such as saline at the beginningof a procedure to clear resident fluids and/or emboli from a site,followed by the introduction of a pharmaceutical solution, followed bythe removal of the pharmaceutical solution and the subsequentintroduction of a neutral solution. In such a use, the saline solutionwould be confined in the first irrigant reservoir 24 b, which would beinfused by actuating the handle 20 as in the embodiment of FIG. 4Adescribed above. Subsequently, the contents of the second irrigantreservoir 24 c, such as a thrombolytic agent, dye, contrast agent orother formulation, is inserted by rotating irrigant reservoir 24 c inline with the irrigant reservoir piston 22, and similar actuation oftrigger 20. Once the desired effect provided by the solution ofreservoir 24 c has been achieved, the solution may be rinsed from thevessel by rotating the dedicated irrigant reservoir 24 d into place andactuating the fluid exchange system as above. Similarly, a variety ofaspirant chambers (not shown) can be used to facilitate collection andtesting of the aspirant fluid by segregating discrete volumes intocontainers that can be processed for analysis.

FIG. 5B is an embodiment where two different irrigant fluids can bedelivered at equal time and measure in a pair of cartridges 243, 24 fthat are designed to be delivered through one or a pair of irrigantlumens 2, 2′ such that one irrigant lumen 2 delivers fluid distal to apredetermined point at the target site and the other irrigant lumen 2′delivers fluid proximal to a predetermined point at the target site. Insuch a case, each of the two irrigant lumens 2, 2′ has a dedicatedirrigant port or ports located at the distal end of the catheterelement. The division of the irrigant reservoir 1 into two components 24e, 24 f allows for the selective introduction of irrigant fluids, whichmay be the same solutions or different solutions at two or more pointswithin the target site. The predetermined point in the target site thatseparates the proximal and distal delivery of irrigant fluid may be anaspirant port located therebetween (as in the embodiment of FIG. 2D) orany other structure where separation of irrigant fluid is desired. Forexample, some irrigants may mix advantageously only at the exchange siteand could not be combined outside the body based on their chemicalreactivity.

FIG. 6 is a tabletop version of the fluid exchange device of theinvention. As is described elsewhere herein, the fluid exchangeapparatus of the invention may be controlled by the simple mechanicaloperation of a device by a user or by an electronic system that controlsa mechanical or electrical pump- or valve-driven system to control theirrigant 1 and aspirant 4 reservoirs. In the embodiment of FIG. 6, avariable position lever 30 drives the stroke of a dedicated piston 22,23 that forces fluid from the irrigant reservoir and draws fluid intothe aspirant reservoir. As with the embodiments described above, thecycle and the volume of the reservoirs or motion of the pistons can bealtered to match the fluid exchange volume needed for any flow in thevessel or body conduit. Because the rotation of the individual levers isvariable, the ratio of fluid exchange can be achieved by differentpositioning of the lever arms 31, 32 rather than by altering the volumeof the individual irrigant 1 and aspirant 4 reservoirs. Although thisembodiment shows the mechanical application of force through levers, atabletop version of the apparatus of the invention is advantageous whenelectronically controlled pumps are provided to control the fluidexchange and fluid exchange ratios. The embodiment of FIG. 6 also mayinclude an in-line air trap 33 for the irrigant reservoir 1 and/or afilter 34 for the aspirant reservoir 4. As it may be advantageous toeliminate debris upon extraction of irrigant fluid and/or prevent airupon entry of irrigant fluid, the inclusion of a filter or trap 33, 34for air and/or emboli is appropriate in some cases.

FIGS. 7A and 7B show the internal structure and function of a fluidexchange device 40 where a pair of reservoirs control fluid flow via theforce exerted by pistons or plungers following the action of a trigger20 and handle 21 connected to or integral with a lever 36 that rotatesabout a pivot 35. In this embodiment, the actuation of the trigger 20rotates the level 36 about pivot 35 and forces the irrigant reservoirpiston 22 into the irrigant reservoir 1 and simultaneously withdraws theaspirant reservoir piston 23 out of the aspirant reservoir. From therelaxed position (FIG. 7A), the trigger 20 can be activated to drive thepistons 22, 23 through either a direct coupling or a mechanism forincremental cycles. If desired, the trigger 20 can return to the relaxedposition after a cycle from spring action in the handle or pivot 35other automatic return mechanism. The reservoirs may be integral to thedevice 10 or the volume of the reservoir 1 may be attached to a separatereservoir (not shown) together with the appropriate lumens, andpreferably in-line one-way valves, to facilitate the exchange betweenthe separate reservoir and the chamber of the device. In the formerembodiment, the reservoirs are integral to the handle-operated devicesuch that the piston exerts a direct force on the irrigant 1 and/oraspirant 4 reservoir to exert the force necessary for fluid exchange. Inthe above embodiment, the internal structure of the device acts as anin-line chamber that is intermediate between the separate reservoir andthe lumen such that irrigant fluid residing in a separate reservoir isdrawn into the chamber prior to being expelled from the chamber throughthe irrigation lumen. In this embodiment, a pair of lumens are required,a first intermediate lumen connecting the separate reservoir to thechamber, and a second lumen communicating the irrigant fluid from thechamber through the irrigant lumen and via the irrigant ports to thetarget exchange site.

FIG. 8 is a preferred embodiment of the invention having a trigger 20that is squeezed by the hand to operate a syringe that acts as theaspirant reservoir 54 and the irrigant reservoir (not shown). As thetrigger 20 moves toward the body of the handle 21, the force istransmitted both to the piston 55 dedicated to the aspirant reservoir 54and a separate piston (not shown) dedicated to the irrigant reservoir.Although the internal configurations can be varied to incorporate othermechanical expedients, the orientation of the lever 56 and pivot 62 ofthe present embodiment provide an advantageous mechanism for a 1:1 ratiofluid exchange. The action of trigger 20 is communicated to a lever 56that is connected to the trigger 20 by a first terminal lever connector58 a. When the trigger 20 moves toward the body of the handle 21, theforce exerted on the lever 56 rotates the lever 56 around pivot 57 toexert a force, via a second terminal lever connector 58 b that isattached to an irrigant carriage 52. Simultaneously, the motion of thetrigger 20 exerts force on a second lever (not shown) that is connectedto the aspirant carriage 51 in a similar matter as for the irrigantcarriage 52. The motion of the trigger 20 provides a simultaneous butopposite force on the aspirant cartridge 51 compared to the irrigantcartridge 52. The simultaneous forces that are applied to the pistonsdedicated to the irrigant reservoir and aspirant reservoir 54,respectively, occur in opposite directions to yield a substantiallyequivalent volume exchange into the aspirant reservoir 4 and out of theirrigant reservoir 1 via the aspirant and irrigant lumens 4, 2respectively. The motion of the irrigant carriage 52 is translated tothe piston dedicated to the irrigant reservoir by virtue of a connector53 that is noncompressible and that is aligned with the length of theirrigant reservoir 1.

As noted specifically with the embodiments described at FIG. 4A herein,the irrigant and aspirant reservoirs 1, 4 may be interchangeablesyringes or cartridges that can be inserted and removed to introducespecific solutions or fluid volumes. In a preferred embodiment, theirrigant and aspirant reservoir 1, 4 may be molded into the body of thedevice such that the fluid volumes for the irrigant and aspirantreservoirs are separately filled via a fixture that acts as an inputvalve to the irrigant and/or aspirant reservoir. The irrigant andaspirant reservoirs 1, 4 preferably have removable fixtures at theoutput 60 thereof for attachment of the respective lumens 2, 3.

The motion of the trigger 20 is rendered linear and reproducible byslots 61 cut into a portion of the trigger 20 that are engaged by thefirst pivot 57 and the second pivot 61 such that the body of the handle21 and/or the trigger 20 slidingly move about either of the pivotstructures. A second lever 63 operates parallel to the lever 56 toenable the trigger 20 to travel smoothly along its path. Thisconfiguration provides for reproducible motion of the trigger 20relative to the body of the housing 21 and also facilitates attachmentof a spring 62 that biases the trigger in the forward position so thatactuation of the trigger 20 relative to the handle 21 produces acomplete cycle that translates into a defined movement of both theirrigant cartridge 52 and the aspirant cartridge 51. The volume exchangeratio provided by the device of this invention may be altered bychanging the relative lengths of the lever 56 relative to the pivot 57or by altering a ratcheting mechanism disposed at the connection pointbetween the lever 56 and the irrigant cartridge 52 such that a completecycle of the trigger 20 from the forward most position when moved towardthe body of the handle 21 constitutes a complete cycle that moves theirrigant 52 and/or aspirant cartridge by fixed distance. The springtension automatically returns the trigger 20 to the forward mostposition to prepare for a second cycle.

FIG. 9A is an embodiment where the travel of the lever in the fluidexchange device is adjustable so that the amount of fluid displaced in asingle cycle can be controlled, and both the distance traveled and theforce generated can be adjusted by relative positions of the trigger 20and the handle body 21. The embodiments of FIGS. 9A and 9B illustratethe ability to alter the fluid flow parameters of the fluid exchangedevice by changing the configuration of the mechanical components thatexert force on the irrigant reservoir 1 and aspirant reservoir 4,respectively. FIG. 9B illustrates the adjustment of the pivot point 57 ato produce different flow ratios and peak pressures based on therelative position of the pivot point 57 a about which the trigger 20rotates. In such an embodiment, if more fluid flow is desired theapparatus can be easily adjusted to accomplish a variable number offlows for a given grip cycle. The travel distance provided by the motionof the trigger 20 as exerted at the point of attachment by the secondterminal lever connector 58 c dictates the amount of fluid flow expelledfrom the irrigant and/or aspirant reservoir 1, 4 based on the action bya syringe or aspirant reservoir piston or carriage as described above.Accordingly, an increase in the motion of a piston compressing fluid inan irrigant or aspirant reservoir or chamber, due to changing the pivotpoint, results in an increased exchange rate for a given activation ofthe trigger 20. As is shown in FIGS. 9A and 9B, the adjustment to thedegree of travel of the trigger 20 relative to the handle 21, whencombined with aspiration 51 and irrigant 52 carriages and reservoirs asdescribed in, for example FIG. 8 above, produces the variable fluid flowof this embodiment. As with the embodiments described above, themechanical movement of the trigger 20 relative to the handle 21 istranslated into fluid flow from an irrigant reservoir 1, via irrigationlumen 2, aspiration lumen 3, and aspirant reservoir 4 by theconfigurations described herein.

FIG. 10 is a hand-held fluid exchange apparatus of the invention whereina ratchet mechanism provides for incremental movement of a piston, inthis embodiment, a general set of pistons 71, 71 a for driving fluid outof the irrigant reservoir 1 and into the aspirant reservoir 4,respectively. As in the embodiment of FIG. 8, the motion of a trigger 20relative to a body handle 21 completes one cycle. This embodiment mayalso contain a mechanical or electrical counter that provides a readoutindicating the number of cycles that have been performed, the volume offluid introduced or removed, or the amount of fluid present, orremaining in either reservoir. In this embodiment, the motion of thededicated, geared piston 71 in the irrigant reservoir 1 is controlled bythe ratchet mechanism which is comprised of the trigger 20, a pivot 70,about which the trigger 20 rotates, and gear 70 b that engages a firstratchet wheel 77. Preferably, the ratchet mechanism is one-way such thatmotion of the trigger 20 toward the body handle 21 rotates the firstratchet wheel 72 that rotates to advance or contract the piston 71. Inthe example of FIG. 10, actuation of the trigger 20 about pivot 70 atranslates to rotation of the first ratchet wheel 72 via gear 70 b. Therotation of the first ratchet wheel 72 is translated to the gearedpiston 71 and this rotation is in turn translated to a second ratchetwheel 73 that rotates in the opposite direction to the first ratchetwheel 72 that is in turn connected to a geared piston 71 a in the otherreservoir.

In the embodiment of FIG. 10, the device is designed to be hand-operatedsuch that the manual actuation of the trigger 20 causes automatic motionof the two ratchet wheels 72, 73 and the geared pistons 71. Theequivalent dimensions of the reservoirs 1, 4, pistons 71, 71 a, and thetwo ratchet wheels 72, 73 shown in FIG. 10 yields an approximate 1:1fluid exchange ratio. In addition to altering the dimensions of theaspirant 4 or irrigant 1 reservoirs, the alteration of the fluidexchange ratio can be achieved by altering the dimensions of the ratchetwheels 72, 73.

FIG. 11 shows the principles of a fluid exchange device with asegregated irrigant 75 and aspirant chambers 76 each having a dedicatedinflow and outflow line. In this embodiment, the inflow line of theirrigation chamber 75 is an irrigation inflow line 2′ that communicatesfluid held in the irrigation reservoir 1 to the irrigation chamber 75.The fluid is drawn into irrigation chamber 75 by the dedicated piston 22and is subsequently expelled through the irrigation lumen 2 into thetarget site for fluid exchange as described previously. Similarly, fluidis drawn from the target site through the aspiration lumen 3 and intothe aspiration chamber 76 by operation of the dedicated piston 23 whosemotion both pulls fluid through the aspiration lumen 3 and into theaspiration chamber 76, but also expels fluid from the aspiration chamber76 to the aspiration reservoir 3, via the aspiration reservoir outflowline 3′. This embodiment of the invention operates much like atwo-stroke engine wherein fluid is pulled into the irrigation 76 andaspiration 75 chambers and subsequently expelled through the appropriatelumen. To control the flow of fluids, each of the dedicated inflow andoutflow lines for each chamber have valves 77 a, b, c, d that controlthe fluid flow. For example, when fluid is drawn into the irrigationchamber 75, a valve 77 a on the chamber inflow line 2′ is opened whilethe piston 22 is pulled back. Subsequently, the inflow valve 77 a closesand an outflow valve 77 b that is in line with the irrigation lumen isopened while the irrigation chamber piston 22 is forced into theirrigation chamber 75 to expel fluids through the irrigation lumen 2.Similarly, when the action of the aspiration chamber piston 23 is usedto draw out fluid into the aspiration chamber 70 via aspiration lumen 3,an inflow valve 77 d on the aspiration chamber inflow line 3 is openedand the in-line valve 77 b in the aspiration chamber outflow line 3′ isclosed. To expel fluid from the aspiration chamber 76 through theoutflow line 3′ and into the aspiration reservoir 4, the in-line valve77 d on the aspiration lumen 3 is closed and the in-line valve 77 c onthe aspiration reservoir outflow line 3′ is opened. As for theembodiments described above, the action of the individual pistons 22 and23 used to cause the fluid flow throughout the system can be controlledmanually by mechanical expedients affixed to the pistons. Alternatively,electronic circuitry can control the speed motion and cycle parametersof both pistons such that the fluid flow is electronically controlledaccording to a user interface or a predetermined fluid exchange profile.As will be apparent to one of skill in the art, the cycling action ofthis embodiment produces a pulsatile flow with the relative motion ofboth pistons 22, 23. Moreover, the particular minimum and maximumpressures in each pulsatile flow can be controlled by the relativeaction of the pistons 22, 23.

In another embodiment, the in-line valves are not actively controlled,but are provided as simple one-way valves that only allow fluid inflowfrom the irrigation 1 reservoir into the irrigation chamber 75 and,likewise only allow fluid outflow from the irrigation chamber 75 throughthe irrigation lumen 2. On the aspiration side of the system, one-wayvalves allow fluid flow only from the aspiration lumen 3 to theaspiration chamber 76, and from the chamber 76 to the aspirationreservoir 4. In use, when the device is activated, the piston plunger ineither chamber will produce a positive flow through the lumen. When thelever begins to relax, the one-way valve will close and the irrigationreservoir 1 will fill the chamber. On the aspiration side, one-wayvalves on both the lumen 3 and the reservoir 4 ensures that the aspirantfluid is purged into the reservoir and, during relaxation, the aspirantis extracted from the exchange site via the aspiration lumen 3.Actuation of the pistons simultaneously causes simultaneous fluid flowto and from the target site while a ½ cycle out of phase yields atransient pressure increase within the system.

FIGS. 12A and 12B show a hand-held fluid exchange apparatus configuredas a compressible handball with the internal volume divided intoirrigant and aspirant aspirant chambers 78, 79 in series with dedicatedinflow and outflow lines connecting irrigation 1 and aspiration 4reservoirs, respectively. With a fluid impermeable wall disposed betweenthe irrigant 78 and aspirant 79 chambers, the collapse of the ball underforce will circulate the fluids appropriately. Referring to FIG. 12A,the apparatus is divided into an irrigation chamber 78 and an aspirationchamber 79 by a fluid impermeable barrier 80 that completely segregatesthe two chambers 78, 79 within the device. The expansion and contractionof the irrigant chamber 78 causes fluid flow through a dedicated inflowline 2′ between the irrigation reservoir 1 and the irrigant chamber 78and out to the target exchange site via the irrigation lumen 2 andterminates at the target site as in the other embodiments describedherein. Similarly, aspirant fluid is drawn in through the aspirationlumen 3 into the aspiration chamber 79 and out through the dedicatedaspiration chamber outflow line 3′ and into the aspiration reservoir 4.As in the embodiment of FIG. 11, one-way flow valves are advantageouslydisposed in each inflow and outflow line between the lumen and chamber,and chamber and reservoir. Thus, a one-way flow valve 81 a allows fluidflow only in the direction from the irrigation reservoir, via inflowline 2′, into the irrigation chamber 78. The fluid inside the irrigationchamber 78 may only flow in the direction through one-way valve 81 b andout through the irrigation lumen 2. Aspiration fluid entering aspirationchamber 79 via aspiration lumen 3 may enter only in the directionthrough one-way valve 81 c and aspiration fluid inside the aspirationchamber 79 may pass only in the direction of the aspiration reservoir 4through one-way valve 81 d.

Referring to FIG. 12B, pressure exerted on the compressible structure ofthe device, as indicated by the bold arrows in FIG. 12B, compresses bothirrigant chamber 78 and aspirant chamber 79 such that fluid flows in thedirection of the arrows i.e. irrigant fluid flows through one-way valve81 b, through irrigation lumen 2 and to the target exchange site.Aspirant fluid flows from the aspiration chamber 79 through the one-wayvalve 81 d and into the aspiration reservoir 4. Fluid flow is preventedby one-way valves 81 c and 81 a from entering either the aspirationlumen 3 or the irrigation reservoir 1. Upon relaxation, the outersurface of the handball moves in a direction opposite to the bold arrowsin FIG. 12B and the flow is reversed. Thus, fluid flows from theirrigation reservoir 1 through the one-way valve 81 a and into theirrigation chamber 78. Likewise, fluid flows from the aspiration lumen3, through one-way valve 81 c, and into the aspiration chamber 79. Thisconfiguration is similar to the embodiment of FIG. 11 because a chamber78 or 79 is provided at an intermediate position between the exchangesite and the reservoir such that a volume of fluid is held at anintermediate position between each reservoir 78, 79 and the exchangesite for purposes of exerting control over a discrete volume of fluidseparate from the irrigation and aspiration reservoirs 1, 4.

However, the compressible handball configuration can be constructed toallow direct manipulation of the irrigation reservoir 1 to expel fluidwhile simultaneously collecting aspirant fluid within the discretestructure of the handball itself. FIGS. 13A and 13B show a handball pumpconfigured with an internal reservoir of irrigant and a flexible barrier82 to separate the irrigant and aspirant reservoirs 1, 4, which aredisposed inside the handball. Referring to the embodiment of FIG. 13A,prior to connection of this embodiment of the invention to a catheterelement, the irrigant reservoir 1 is preferably filled with fluid tosubstantially encompass the entire internal volume of the handball. Theflexible and fluid impermeable barrier 82 deforms towards the outer wallof the handball to accept irrigant solution and to simultaneouslyminimize the internal volume of the aspirant reservoir 4. When used in aclinical setting, the irrigant reservoir 1 is filled with thepharmaceutically acceptable composition to be used as the irrigant andthe apparatus is sealed and may be sterilized while intact. Beforeusing, the device is connected to the irrigation lumen 2 and aspirationlumen 3 which may be filled with fluid to establish the substantiallyclosed loop as described previously. As in the embodiment of FIGS. 12Aand 12B, one-way valves 83 a, 83 b are positioned in-line between theirrigant reservoir 1 and the irrigation lumen 2, and between theaspiration lumen 3 and the aspirant reservoir 4. As the handball iscompressed, fluid flow generally occurs in the area of the arrows toforce fluid out of the irrigant reservoir 1, through the irrigationlumen 2 and into the target site while any backflow is prevented by theone-way valve 83 a. Accordingly, aspiration fluid is drawn through theaspiration lumen 3 and collects in the aspirant reservoir 4. FIG. 13Bshows an embodiment of the invention wherein approximately half of theirrigant solution has been expelled through the irrigation lumen 2,exchanged at the target site, and collected back in the aspirantreservoir 4 via aspiration lumen 3. As above, fluid flow generallyoccurs in the direction of the arrows as the internal irrigant volume isexchanged between the irrigant reservoir 1 and the aspirant reservoir 4.

As noted above, the principal of the invention may be achieved by bothuser operated, generally mechanically controlled embodiments of theinvention, or through electronically controlled apparatus that usuallyrequire electronically controlled pumps and/or valves. In the embodimentof FIG. 13C, a volume metric pump 86 with an internal balloon 85 isprovided to achieve the fluid exchange function of the invention.Generally, the device is comprised of a housing 84 that is preferablysubstantially rigid and which contains an internal irrigant reservoir 1and aspirant reservoir 4 connected to dedicated irrigation andaspiration lumens 2, 3, as described previously. Volumetric control isachieved by selectively expanding an internal balloon 85 within thehousing 84 to be positioned in either the irrigant reservoir 1 oraspiration reservoir 4. As with the embodiments of FIGS. 13A and 13B, ata preliminary point in the use of the device the irrigant reservoir 1 isgenerally full and the internal volume balloon 85 is confined in theaspirant reservoir such that the internal volume of the balloon 85 ismaximized within the aspiration reservoir4 and does not displace asubstantial volume of the irrigant reservoir 1. This allows the maximumamount of irrigation fluid to exist within the irrigant reservoir 1prior to use of the device. As the fluid exchange process occurs, thevolumetric pump 86 functions by forcing a portion of the internal volumeof the balloon 85 into the irrigant reservoir 1. The volumetric pump 86may be controlled by the user or through an electrical circuitry thatprovides an output reading to dictate the volumes or relative percentagevolumes between the reservoirs 1, 4. As the volume exchange processcontinues, the internal volume of the balloon 85 is transferred to agreater and greater degree from the aspirant reservoir 4 to the irrigantreservoir 1 to displace the internal volume of the irrigation fluid. Ata half-way point, the internal volume of the balloon is equally disposedbetween the two reservoirs (assuming that the beginning volume of thetwo reservoirs is equal) and the volumes of the fluid contained in boththe irrigant 1 and aspirant 4 reservoirs is equal. As describedpreviously, a simple modification of the dimensions of the apparatusallow variation of the volume exchange ratio from a 1:1 value to anyprescribed ratio dictated by the clinical circumstances.

FIG. 14 shows a side view of the device where the irrigation 90 andaspiration 91 fluid impermeable chambers are contained in the same,preferably rigid housing 92 and are separated by a centrally disposedpiston 93 that engages the interior of the housing 92 about the entireperiphery thereof to segregate the irrigant fluid from the aspirantfluid and allows the piston 93to slide within the housing 92. By movingthe piston 93 within the interior of the housing, typically from oneextreme end to another, the irrigant is forced out of the irrigantchamber 90 and into the irrigation lumen 2. Fluid exchanged at thetarget site is collected through the aspiration lumens and into theaspirant chamber 91. Thus, in the example of FIG. 14, when the piston 93slides from one end to the other, the irrigant chamber 90 expelsirrigant, while the aspirant chamber 91 simultaneously draws in aspirantfluid. Then, as the piston 93 is moved back in the other direction, theirrigant chamber 91 refills itself with fluid from the irrigantreservoir 1 while the aspirant chamber 91 expels its contents into theaspiration reservoir 4. As in other embodiments described herein, thissimple, compact arrangement allows for simultaneous irrigation andaspiration and yield a pulsatile flow. Although shown as a cylindricalhousing 92, the construction and arrangement of the input, output,reservoir and piston elements could be altered without departing fromthe spirit of the invention. In the embodiment of FIG. 14, the piston isdesigned to move repeatedly and reproducibly within the housing to expeland collect a defined volume of fluid with each operation cycle.

The volume of fluid exchanged at the target site with each cycle of thepiston 93 is substantially equivalent to the internal volume of thehousing 92 assuming that the piston 93 is moved from one extreme toanother extreme inside the housing 92 during each cycle of the operationof the device. This embodiment also demonstrates, as in the foregoingembodiments, that the fluid exchange device of the invention is readilyadapted to be controlled either manually, in this case through theapplication of force to a handle 94 attached to the piston 93, or byelectronic control, which in this embodiment would be provided by asimple pump or electrical or magnetic force to move the piston 91 withinthe housing 92. The separation of the irrigant and aspirant reservoirs1, 4 from an irrigant and aspirant chamber 90, 91 permits the device tobe repeatedly cycled to draw a defined volume into each chamber 90, 91for propulsion through the irrigation lumen 2 and collection through theaspiration lumen 3. In an alternate embodiment, the entirety of theirrigant fluid to be exchanged at the target site would begin containedwithin an aspirant reservoir that is entirely located within the housingsuch that movement of the piston 91 from one extreme of the housing 92to the other would communicate the entire volume of the irrigantreservoir 1 through the irrigation lumen 2, to the target exchange site,and back into the aspirant reservoir 4 via the aspiration lumen 3. Afurther example of this embodiment is shown in FIG. 15 below, having analternate mechanical expedient for propelling fluid from the irrigantreservoir 1 into an aspirant reservoir 4.

In the embodiment of FIG. 15, the irrigant and aspirant reservoirs 1,4are separated by a fluid impermeable barrier 95 that is movable about athreaded axis 97 or other structure that passes within a slidable member96 that rotates and slides about the threaded axis 97 to move thebarrier 95 along the axis 97 to propel the irrigant fluid. Ideally, theslidable member 96 provide for a high rate of translation, while themember 97 provides for fine travel about the threaded axis 97. Thesliding element can be selectively disengaged from the threads to allowit to slide rapidly along the threaded axis for gross adjustment. Whenengaged, the sliding element can be rotated for fine adjustment.Interior to the sliding element is a mechanism which permits thisselective thread engagement by retracting the thread contact whenactivated.

Referring to FIG. 15, this embodiment of the fluid exchange device iscomprised of two main elements to achieve a configuration that allowsfor the body or cylinder actuation of both syringes in the desired andopposite manner. Essentially, a unitary body 101 connects of one syringeelement 102 a and is connected rigidly to the piston 103 b of the othersyringe element. A slidable element 104 engages the unitary body 101 andslides reproducibly in engagement therewith. As shown in FIG. 16, theslidable element 104 is also attached to the cylinder 103 a of onesyringe and the piston 102 b of the other. Motion of the slidableelement 104 exerts a force withdrawing one piston while advancing theother and braces the application of force by the attachment of the body101 or element 104 to the cylinder or body of each syringe 102 a, 103 a.The design could incorporate existing syringes or have the syringeelements molded into the piece. There are several distinct advantages tothis embodiment. One is that it ensures a 1:1 exchange ratio in terms oftravel distance between the syringes. Another is that the geometricarrangement allows for a balancing of the forces involved in the device.Finally, the realization of the complex mechanics through just twomoving parts is a significant advantage for the manufacturing andefficiency of the device.

As described above, the element of turbulence is important to theefficacy of the device. Since fluids tend to assimilate to laminar flow,proximity of the irrigant ports or perforations that facilitatesturbulence is important for optimal rinsing of the interior of a bodystructure. For this reason, translation of the catheter element mayaccompany the irrigation or aspiration or both. All embodimentsdescribed herein can be manually translated by means of the operator'shand. Additionally, the catheter can be translated using an automatedtranslation system similar to those used in IVUS and similarapplications. Alternatively, the catheter could be translated by anelement incorporated into the fluid delivery device. Referring to FIG.17A a simple mechanism that could be used to realize this self-advancingaspect. When the catheter 7 element is moved to the left in thedirection of the arrows in FIG. 17A, the round engaging element 110slides up in the slot 111 and engages the catheter 7 to move it to theleft as well.

FIG. 17B shows the same mechanism. Once the catheter element 7 is slidto the right the round engaging element 110 slides down in the slot 11and allows the catheter element 7 to slide freely to the right in thedirection of the arrow without interacting or affecting the catheter'sposition. This allows for the selective retraction or advancement of thecatheter 7 by a predetermined amount with each squeeze of the device.There are many ways in which this element could be realized. Thesimplest would be an apparatus that selectively grasps the catheter whenmoving one direction and idles or does not grasp when moving in theopposite direction. A guiding track that biases the element could beused to apply pressure and grasp the catheter moving in one directionand then release and allow idle sliding to the reset position in theother direction. This element could be selectively engaged by theoperator when needed, and could be developed to allow for selectionbetween advancement and retraction of the catheter.

In the present preferred embodiment of the fluid exchange device, it isnecessary to have a reset force supplied by an element such as a springinherent in the device. This reset force is added to the resistance inthe system that must be overcome by the operator to utilize the device.In some cases, an embodiment where this force was minimized oreliminated would allow more of the force generated by the operator to bedirected to the work the device is performing and not to overcoming thereset force element. Referring to FIGS. 18A-18C, this function could beachieved through the use of a staged device. FIG. 18A shows a simplemechanical way in which the two sides of the device could be linkedmechanically. It is important in this embodiment that the two sides belinked mechanically so that they behave in an equal and opposite manner.This is necessary so that the trigger can be actuated repeatedly in thesame manner but engage just one of the sides while still driving theentire system. This allows the benefit of having the operator notrealize the changes occurring internally in the device. The squeezeswould not feel substantially different. In this embodiment, the firstsqueeze would activate the two chambers and the second squeeze wouldreset the two chambers. A simple mechanical setup could achieve thisresult. Similar mechanisms are commonly used in objects such asretractable ball point pens. Essentially, an element attached to thetrigger element would be slightly biased to selectively engage one sideor the other of the device. FIG. 18B shows a top view of the tracklayout that would guide the selectively engaging element of the trigger.With the two sides linked mechanically to travel in equivalent andopposite manners as described elsewhere, the force of the triggerelement could always be applied in the same manner with varying effect.With the aid of the minimal return force element, the trigger is broughtback to its full and extended position and biased to one side so that itwill slip into the opposite track for the next actuation of the trigger.After that actuation, as the trigger is returning to its defaultposition, it will be biased to one side of the device and slip easilyinto the track of the opposite side.

FIG. 18C is a diagram of how the system could be achieved such that eachtime the trigger is expanded, it engages the other side of the deviceand pulls it back when squeezed.

Many features have been listed with particular configurations, options,and embodiments. Any one or more of the features described may be addedto or combined with any of the other embodiments or other standarddevices to create alternate combinations and embodiments. Although theexamples given include many specificities, they are intended asillustrative of only a few possible embodiments of the invention. Otherembodiments and modifications will, no doubt, occur to those skilled inthe art. Thus, the examples given should only be interpreted asillustrations of some of the preferred embodiments of the invention.

1-24. (canceled)
 25. A method for achieving fluid exchange within alocalized region of the body comprising: introducing a catheter elementinto the body wherein the catheter element is comprised of an irrigationlumen terminating with at least one irrigation port at a distal end ofthe catheter element and an aspiration lumen terminating with at leastone aspiration port; advancing the distal end of the catheter element tothe localized region of the body; activating a trigger of a fluidexchange apparatus comprising an irrigation reservoir in fluidconnection with the irrigation lumen and having means for controlleddelivery of irrigant fluid from the irrigation reservoir through theirrigation lumen to the localized region and an aspiration lumen havingmeans for controlled collection of aspirant fluid, wherein theactivating step produces a controlled delivery of irrigant fluid fromthe irrigation reservoir through the irrigation lumen and wherein amechanical linkage causes removal of aspirant fluid from the localizedregion through the aspiration lumen; and wherein this step of activatingthe trigger produces turbulent fluid exchange at the target site fromthe simultaneous delivery of irrigant fluid and removal of aspirantfluid.
 26. The method of claim 25 wherein irrigant fluid is contained ina cylinder with a dedicated piston and the activating step forces fluidfrom the cylinder through the irrigation lumen.
 27. The method of claim25 wherein the activation step collects aspirant fluid from the targetsite through the aspiration lumen and passes the aspirant into acylinder with a dedicated piston.
 28. The method of claim 26 furthercomprising the step of providing irrigant fluid in a replaceablesyringe.
 29. The method of claim 25 further comprising inflating anoccluding element proximal of the at least one irrigation port and theat least one aspiration port such that substantially all of the fluidexchange occurs distal of the occluding element.
 30. The method of claim29 wherein the inflating step is comprised of inflating a balloon. 31.The method of claim 25 wherein the irrigant fluid is introduced throughan irrigation chamber having an inflow line in fluid communication withthe irrigation reservoir and an outflow line in fluid communication withthe irrigation lumen.
 32. The method of claim 25 wherein the aspirantfluid is removed through an aspiration chamber having an inflow line influid communication with the aspiration lumen and an outflow line influid communication with the aspiration reservoir.
 33. The method ofclaim 25 wherein the trigger is activated by hand.
 34. The method ofclaim 27 wherein the trigger is integrally connected to the cylinder andthe dedicated piston.
 35. The method of claim 25 wherein the aspirantfluid passes through at least one one-way valve in the fluid pathway ofthe aspiration lumen and the aspiration reservoir.
 36. The method ofclaim 25 wherein the step of activating the trigger achieves apredetermined ratio of fluid volume exchange between irrigant fluid andaspirant fluid at the target site.
 37. The method of claim 36 whereinthe predetermined ratio is approximately 1:1.
 38. The mechanical deviceof claim 36 wherein the predetermined ratio is between approximately 1:2and 2:1.